Toy building block



FIG. 1 is a top perspective view of a toy building block showing my new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a side elevational view thereof, the side opposite being identical;

FIG. 5 is a top plan view thereof; and

FIG. 6 is an end elevational view thereof; the side opposite being identical. 

The ornamental design for a toy building block, as shown and described. 